In conventional medical diagnostic imaging, the object is to obtain an image of a patient's internal anatomy with as little X-radiation exposure as possible. The fastest imaging speeds are realized by mounting a duplitized radiographic silver halide material between a pair of fluorescent intensifying screens for imagewise exposure. About 5% or less of the exposing X-radiation passing through the patient is adsorbed directly by the latent image forming silver halide emulsion layers within the duplitized material. Most of the X-radiation that participates in image formation is absorbed by phosphor particles within the fluorescent screens. This stimulates light emission that is more readily absorbed by the silver halide emulsion layers.
Examples of radiographic silver halide materials that are useful for medical diagnostic purposes are described in U.S. Pat. No. 4,425,425 (Abbott et al.), U.S. Pat. No. 4,425,426 (Abbott et al.), U.S. Pat. No. 4,414,310 (Dickerson), U.S. Pat. No. 4,803,150 (Dickerson et al.), U.S. Pat. No. 4,900,652 (Dickerson et al.), U.S. Pat. No. 5,252,442 (Tsaur et al.), and U.S. Pat. No. 5,576,156 (Dickerson), and Research Disclosure, Vol. 184, August 1979, Item 18431.
These radiographic materials are typically processed after exposure to provide a black-and-white image using developing and fixing compositions that are known in the art.
Development is usually the first step to providing a useful black-and-white image in radiographic silver halide materials. Photographic black-and-white developing compositions containing a silver halide black-and-white developing agent are well known in the photographic art for reducing silver ions in silver halide grains containing a latent image to yield a developed black-and-white photographic image. Many useful developing agents are known in the art, with hydroquinone and similar dihydroxybenzene compounds and ascorbic acid (and derivatives) being some of the most common. Such compositions generally contain other components such as sulfites, buffers, antifoggants, sequestering agents, halides and hardeners.
The development step is generally followed by a fixing step in which a photographic fixing agent is used to remove silver from non-imaged areas of the radiographic material. Various inorganic and organic fixing agents are known for this purpose. In most instances, development and fixing are distinct steps are described in U.S. Pat. No. 6,040,121 (Fitterman et al.), but in some instances, development and fixing are combined as described in U.S. Pat. No. 6,074,806 (Fitterman et al.).
Problem to be Solved
The radiographic silver halide described and used in the art traditionally contain various silver halide emulsion layers coated on a transparent film support (often coated on both sides) so the resulting images can be viewed using light boxes. However, in many remote parts of the world, light boxes are not available, thereby severely limiting the usefulness of traditional radiographic materials. In addition, in many parts of the world, there is insufficient electrical power to generate X-radiation using traditional high-power imaging machines, or such machines are too heavy for convenient transport to remote sites.
There is a need to find a means to provide meaningful radiographic imaging and diagnostics without the need for a light box. It would be useful if there were radiographic silver halide materials that could be processed in a simple fashion with low-power X-radiation equipment to provide images viewable under ambient lighting. While reflective radiographic silver halide materials were developed to solve this problem as described in copending and commonly assigned U.S. Ser. No. 11/091,609 (filed on even date herewith by Dickerson, Duke, Bunch, and Fitterman and entitled “High Speed Reflective Radiographic Material”) and U.S. Ser. No. 11/091,601 (filed on even date herewith by Dickerson, Duke, and Fitterman and entitled “Reflective Radiographic Material with Incorporated Developer”), there was an additional need for simple and effective processing compositions and methods to use with these reflective radiographic silver halide materials.